Process of treating wood



June 16, 1931. w. KRlTcHEvsKY ET AL 1,810,659

PROCESS 0F TREATING WOOD Filed Feb. 14. 1929 atented June i6, 193i` i'WULF KRTCHEVSKY ANDy CARL J'. BECKERT, OF CHICAGO,

v orsics ILLINOIS PROCESS F TREATING WOOD vAmalication led February `14,1929. Serial No. 339,910.

ln the productionof lumber and veneer from black walnut logs, asubstantial loss is occasioned by the necessity for utilizing only .theheart wood which is of the desired color, and discarding the sap woodwhich constitutes twenty'to` thirty percentof the whole log.

- The quality of the sap wood, except for the color, is equal orsuperiorY to that of the l0 heart wood, and this invention relates to amethodof eiecting the coloring of this valuable portion of the walnutlog.

We are aware that various processes of coloring the sap wood have beensuggested,

l5 but in none of the processes has the problem been solved, -from apractical standpoint,

either chemically or physically. The addition of color is expensive,uncertain and unsatisfactory.

wWe have discovered that the coloring matter in black walnut ispresentin the natural sap wood in chemical combination as a glucoside or ester,with some form of sugar, or

with cellulose or lignin. This coloring matter, in the natural growth ofthe wood, be-

comes oxidized or hydrolized very slowly and gradually by changes oftemperature and other: natural causes, the process extending over a longperiodl of years. Naturally,

' 30 therefore, the coloring proceeds from the center outward.

We have4 discovered that this chemical reaction may be hastened by theapplication of heat and pressure and the process completed in a fewhours.

That the theory above expounded is correct is borne out bythe fact thatsapwood and heartwood indiscriminately may be 40 treated by our processwithout change in the color of the heartwood, the sap-wood being coloredto exactly the shade of the heartwood and indistinguishable therefrom,This would seem to prove that a certain definite quantity of thecoloring matter is present in to assist in the material from charring orbreaking down unthe natural wood, which, when developed produces thedesired color.

The apparatus necessary to the carrying out of the process is simple,and consists merely of a pressure type container of the required sizewith pipe connections for the Y admittance of steam. A pressure kettlesuch as contemplated is illustrated in the accompanying drawing in whichthe figure is a perspective View thereof.

The autoclave or pressure-container may be of any desired size havingthe cover 10 with' clamping bolts 11 Jfor securing the cover in place. Asteam admission pipe'is indicated at 12 and a water admission pipe at13.

A steam pressure gauge is indicated at 14 and a thermostatic regulatingunit at 15. Inasmuch as the treatment is by'steam under pressure and asthe temperature is a function of the pressure, a pressure regulatormaybe substituted for the thermostatic regulator if so desired.

Instead of supplying steam. directly to the tank, heat may be applied tothe exterior of the tank, which will vaporize the water therein anddevelop suitable pressure.

In carrying out the process, a quantity. of water equal to approximatelyten percent by weight of' he wood to .be treated is admitted into thecontainer. It is essential that water in at least the uantity indicatedbe present ydrolysis and to protect the der the temperature.- A muchlarger quantity of water may be used if desired, butl the amountindicated has been found to be satisfactory.

After the waterhas been supplied and the container is tightly. closed,steam is admitted at atemperature of from to 160 degrees centigrade withcorresponding pressures. In' l ractice, we have found that a temperatureof from to 140 degrees centigrade with a pressure of from 35 to40'pounds is most satisfactory. With a maintained temperature ther, thatthe time varies in inverse proportion to said temperature and pressure.The proportion however is not direct, it being neither arithmetical norgeometrical, but varies according-to a formula that we have not yetdetermined.

It has also been found desirable in order to facilitate the treatingprocess and to improve the wood fiber, to cook orsoak the material inhot water with some penetrating agent in solution before placing in thecontainer. This, however, is an optional pretreatment that does notaffect the operation of the described process except to lessen the timerequired for its completion.

From the above description it will be apparent that the material eitherin the form of logs, lumber, or veneer may be treated indiscriminatelyas to heartwood and sapwood, no changes in the color of the heartwoodresulting therefrom. This is a very great advantage as it eliminates thenecessity for separating the two classes of wood before treatment.

.While we have dcscrib'ed this process as peculiarly adaptable to thecoloring of black walnut it will be understood that the process isequally applicable to the treatment of other kinds and descriptions ofwood, particularly mahogany and gums in which we have found the samechemical conditions as described in connection with black walnut.

We have attempted to outline the process within the limits that havebeen found to be practical, and feasible.

We realize ,that variations and modifications may be made in the processfollowing its use, by those skilled in the art, and we do not wish to belimited except as indicated in the appended claims.

We claim:

1. The process of treating wood which consists in placing the Wood in acontainer, supplyingwater to the container, and subjecting the materialin the container to steam presy sure above atmospheric.

2. A process for treating sap Walnut which consists in placing the samein a closedvessel in the presence of an amount of water equal to from 10to 60 percent of the weight of the wood and subjecting the contents toahsteam pressure of between and 50 pounds.

' 3. The method of treating` wood which consists in pre-soaking thewood, and then subjecting the wood to steam pressure above atmospheric.

4. A process for treatingr sap Walnut which consists in subjecting thematerial to presoaking, then placing the same in a closed vessel in thepresence of an amount of water equal to from 10 to 60 percent of theweight of the wood and subjecting the contents to a temperature of 120to 160 degrees C., and steam pressure above atmospheric.

ln testimony whereof we have affixed our signatures.

W. KRITCHEVSKY. CARL J. BECKERT.

lUO

